Use ruler and compasses for standard constructions (perpendicular bisector, angle bisector, perpendicular from a point), draw loci of points satisfying given conditions, and use scale drawings and three-figure bearings.

What this dot point is asking

WJEC asks you to use a ruler and a pair of compasses for the standard constructions, to draw loci of points that satisfy given conditions, and to work with scale drawings and three-figure bearings. Constructions must show the compass arcs as evidence of method, because the marks reward the technique, not just a neat line. Loci questions combine the constructions with the idea of a path or region, and bearings link geometry to navigation. The topic appears on both components and rewards accurate, labelled diagrams.

The standard constructions

Each construction is built from compass arcs, which must be left visible.

The construction marks are awarded for the arcs, so never rub them out. Accuracy to within about $2$ mm and $2^\circ$ is expected.

Loci

A locus is a path or region of all points obeying a condition.

So the four constructions are also the four basic loci. The boundary is the locus itself; "nearer to A than B" is the region on A's side of the perpendicular bisector.

Combining loci

Many questions ask for the region satisfying two or more conditions at once.

Scale drawings and bearings

Bearings describe direction for navigation problems.

A bearing is an angle measured clockwise from north, always written with three figures, so $060^\circ$ not $60^\circ$. A back bearing (the reverse direction) differs by $180^\circ$: add $180^\circ$ if the bearing is under $180^\circ$, subtract if it is over. In a scale drawing, lengths are reduced by a stated ratio (for example $1$ cm to $5$ km), so measure on the drawing then convert using the scale, and combine with bearings to find real distances and directions.

Why this matters

Constructions and loci reward careful, accurate drawing and a clear understanding of what each compass technique produces, and they are unusual in awarding method marks for visible arcs rather than written working. Loci that combine two or three conditions test problem solving (AO3), the highest-value objective, and bearings link the geometry strand to real navigation, often combined with trigonometry on harder questions. Neat, fully labelled diagrams with arcs left in are the route to full marks.